Preceding guard rail holder for a scaffolding system

ABSTRACT

Preceding guardrail holder for a scaffolding system, configured for cooperation with guardrails provided with a fastening hook at a longitudinal end. The preceding guardrail holder includes a first and a second cross connection element extending perpendicular to a mounting plate and a retaining plate, which cross connection elements are mutually spaced apart and together bound a fastening hook receiving space for receiving in the fastening hook receiving space the fastening hook of a first guardrail. The distance between the first and the second cross connection element is such that, if the fastening hook is received in the fastening hook receiving space and the first guardrail is not supported otherwise, a recess on a radial inner side of the fastening hook rests on the first cross connection element, and a radial outer side of the fastening hook abuts against the second cross connection element, the first guardrail thereby being wholly supported by the single preceding guardrail holder.

The invention relates to a preceding-guardrail holder for a scaffolding system, an assembly of the preceding-guardrail holder and a guardrail, and a method for arranging the guardrail on the scaffolding system using the preceding-guardrail holder.

BACKGROUND

Scaffolding systems are used in construction and the industry to work at places that cannot be reached from the ground. In scaffolding, two scaffold types can be distinguished, viz. system scaffolds and frame scaffolds.

System scaffolds comprise metal scaffold tubes, and scaffold couplings between these tubes. To vertically disposed scaffold tubes, called standards, there are attached, by means of these couplings, horizontally oriented scaffold tubes, called transverse and longitudinal ledgers. On or to the ledgers, floor parts can be attached to form a floor, in particular multiple floors at different floor levels. The space that is formed by four standards, four transverse ledgers and four longitudinal ledgers is called a scaffold bay.

In frame scaffolds, use is made of scaffold frames which are mutually connected with each other by floor parts. Each scaffold frame comprises two standards which are mutually fixedly connected with each other by at least one transverse ledger. Building up a scaffold bay proceeds in broad outline as follows. First, two vertical scaffold frames are placed at a distance from each other. The scaffold frames are connected at a particular height by means of floors. The assembly of two frame parts and the floors connecting these frame parts is called a scaffold bay.

Both in the system scaffolds and in the frame scaffolds, for the purpose of strengthening a scaffold bay, braces may be fitted between the standards and ledgers. For safety, between the standards, a guardrail may be mounted. The guardrail ensures that a person cannot fall off the floor parts. Also, between the standards a toe board may be mounted, which ensures that things on the floor cannot fall off but are held back by the toe board.

GB 1,051,164 discloses a coupling (“joint”) for connecting a diagonal brace to an upright of a frame scaffold. The joint comprises a joint body which is secured to an upright of a frame scaffold. The diagonal brace is provided at each end with a connecting lug provided with a hole. The joint body is provided with an opening for receiving the connecting lug of the brace. The joint body is further provided with a locking pin slidably mounted in the body and arranged to be inserted through an aperture in the connecting lug of the brace when the brace is coupled to the joint body and whereby the brace is hence secured to the upright. The connection between the joint body and the brace is such that the brace is pivotable around an axis which extends parallel to an axis of the upright to which the joint body is secured.

US 3 360 287 A shows a coupling for coupling ledgers or diagonal braces to the uprights of a scaffold. The coupling comprises two pins placed one above the other and which are attached to an upright. Just as with GB 1,051,164, the ledgers or diagonal braces are provided at both ends with flat connecting lugs. In US′287 each flat connecting lug is provided with a slot or hole through which the pins of the coupling can be slipped. The coupling is further provided with a locking element which hinders the ledgers or diagonal braces being able to fall off the coupling, which would result in failure of the scaffolding system.

A scaffolding system with a guardrail is for instance known from DE 101 12 369 A1. There is shown a guardrail 14 having at both ends fastening hooks for attachment to a standard of the scaffold frame. When building up a new platform level of the scaffold, such a guardrail has the disadvantage that a floor level still unprotected at that moment needs to be entered to be able to mount this guardrail. If no additional provisions and/or means are used, this may be unsafe and in many cases this is also prohibited nowadays. Accordingly, there exists in the market a need for a so-called preceding guardrail. A preceding guardrail is herein understood to be a temporary guardrail which can be placed above a protected floor level to protect an as yet unprotected floor before it is entered. Such a preceding guardrail can be mounted before the scaffold frame has been built up at the level of the preceding guardrail.

The firm Layher, for that purpose, offers the Advance Guardrail (AGR) system. This system consists of two telescopic preceding-guardrail posts and an advanced preceding guardrail. Via an ingenious system the advanced preceding guardrail is mounted to the telescopic preceding-guardrail posts. These preceding-guardrail posts can be mounted, from a particular floor level protected with a preceding guardrail, at the height of an upper, still unprotected floor level and form a temporary preceding guardrail there. After the advanced preceding guardrail has been arranged, the upper floor level can be safely entered to arrange a permanent guardrail there. The disadvantage of this system is that deviating preceding guardrails have to be purchased, which can only be used for the temporary system and which cannot be used further.

SUMMARY OF THE INVENTION

The object of this invention is to provide a preceding-guardrail holder for cooperation with existing guardrails, which preceding-guardrail holder can be used for placing a temporary preceding guardrail on an upper, unprotected floor level.

The invention provides to that end a preceding-guardrail holder for a scaffolding system comprising standards, ledgers and substantially tube-shaped guardrails according to claim 1. More particularly, the invention provides a preceding-guardrail holder which is configured for cooperation with the guardrails of the scaffolding system.

Each guardrail is provided at a longitudinal end thereof with a fastening hook which has a curvature around a curvature axis which is perpendicular to a longitudinal axis of the guardrail. The fastening hook is provided on a radial inner side thereof with a recess, while the distance of the recess to a point on a radial outer side of the fastening hook gradually increases from a first point on the radial outer side to a second point on the radial outer side of the fastening hook, with the second point being more remote from a center of the guardrail than the first point. Such guardrails are already known. An example is the already mentioned guardrail 14 of DE 101 12 369 A1.

The preceding-guardrail holder is provided with a mounting plate and with a retaining plate which extends substantially parallel to the mounting plate. The mounting plate and the retaining plate are mutually connected by a first and a second cross connection element extending perpendicular to the mounting plate and retaining plate. The two cross connection elements are mutually spaced apart and together bound a fastening hook receiving space for receiving the fastening hook of a first guardrail of the above-mentioned guardrails in the fastening hook receiving space. The distance between the first and the second cross connection element is such that, if the fastening hook is received in the fastening hook receiving space and the first guardrail is not supported otherwise, the recess on the radial inner side of the fastening hook rests on the first cross connection element, and the radial outer side of the fastening hook abuts against the second cross connection element, as a result of which the first guardrail is wholly supported by the single preceding-guardrail holder.

Due to this construction of the preceding-guardrail holder, it is possible to insert the fastening hook of a known guardrail in the fastening hook receiving space of the preceding-guardrail holder, and to allow the guardrail to be supported by the preceding-guardrail holder. The preceding-guardrail holder then hangs, as it were, by one end from the preceding-guardrail holder. This makes it possible to place the guardrail from below in a preceding-guardrail holder that is above an as yet unprotected floor level.

Preferably, the preceding-guardrail holder is mounted on a temporary preceding-guardrail post which can be temporarily mounted to a standard. After mounting of the temporary preceding-guardrail post to a standard, the guardrail can be hung by one end in the preceding-guardrail holder. The free end of the guardrail, that is, the guardrail end whose fastening hook has not yet been fitted in a preceding-guardrail holder, is hanging down and can be handled from the lower floor level. To the fastening hook of the freely hanging end, a second preceding-guardrail holder can be attached, which is mounted, for instance, to a second temporary preceding-guardrail post. By moving up this second temporary preceding-guardrail post and securing it to the scaffold frame, the upper floor level is protected by the guardrail, which thereby functions as preceding guardrail.

The preceding-guardrail holder in this way provides an elegant solution for arranging a temporary preceding-guardrail on an upper floor level. This solution makes use of known guardrails, which are typically available on a building site. Accordingly, no new, specialized preceding-guardrails need to be purchased, while safety during arranging is guaranteed. Arranging of the guardrail can simply proceed by hooking the fastening hook into the fastening hook receiving space. This can be done by a single person.

The invention provides in addition an assembly according to claim 16 for arranging a temporary preceding guardrail on a scaffolding system comprising standards, ledgers and substantially tube-shaped preceding guardrails. More particularly, the invention provides an assembly comprising a guardrail and a first preceding-guardrail holder according to the invention. The guardrail is provided at a first longitudinal end thereof with a first fastening hook which has a curvature around a first curvature axis which is perpendicular to a longitudinal axis of the guardrail. The first fastening hook is provided with a recess on a radial inner side. The distance of the recess to a point on a radial outer side of the first fastening hook gradually increases from a first point on the radial outer side to a second point on the radial outer side of the first fastening hook, with the second point being more remote from a center of the guardrail than the first point.

The effects and advantages of the assembly according to the invention are the same as the effects and advantages of the preceding-guardrail holder according to the invention.

The guardrail may be provided at a second longitudinal end with a second fastening hook which has a curvature around a second curvature axis which is parallel to the first curvature axis, with the second longitudinal end located opposite the first longitudinal end of the guardrail. The curvature of the second fastening hook may be opposite to the curvature of the first fastening hook. The second fastening hook may, just like the first fastening hook, be provided on a radial inner side thereof with a recess, while the distance of the recess to a point on a radial outer side of the second fastening hook gradually increases from a first point on the radial outer side to a second point on the radial outer side of the second fastening hook, while the second point is more remote from a center of the guardrail than the first point. The assembly may further be provided with a second preceding-guardrail holder according to the invention, with a first preceding-guardrail post and with a second preceding-guardrail post. The first preceding-guardrail post may, on or near an upper side, be provided with the first preceding-guardrail holder, and at a lower side be configured to be supported by a bracket of the scaffolding system, or a temporary bracket on the scaffolding system. The second preceding-guardrail post may, on or near an upper side, be provided with the second preceding-guardrail holder, and at a lower side be configured to be supported by a bracket of the scaffolding system, or a temporary bracket on the scaffolding system.

The above-described example of the assembly is described in claim 19. With this assembly, the first preceding-guardrail post can be mounted to the scaffold frame, so that the upper side of the first preceding-guardrail post is located above an upper, unprotected floor level. Thereupon, the first fastening hook of the guardrail can be received in the fastening hook receiving space of the first preceding-guardrail holder. The second preceding-guardrail holder can then be attached to the second fastening hook, by inserting the second fastening hook into the fastening hook receiving space of the second preceding-guardrail holder. By finally mounting the second preceding-guardrail post to the scaffold frame in such manner that the upper side of the post is located above the upper floor level, the guardrail offers a protection for the respective floor level. The assembly therefore provides a solution for arranging a temporary preceding guardrail on an upper floor level, utilizing known guardrails.

The invention further provides a scaffolding system comprising standards, ledgers, and the assembly according to the invention.

The effects and advantages of the scaffolding system according to the invention are the same as the effects and advantages of the preceding-guardrail holder and the assembly according to the invention.

The invention further provides a method for arranging a temporary preceding guardrail according to claim 21. More particularly, the invention provides a method for arranging a temporary preceding guardrail on a scaffold, the method comprising:

-   providing scaffold components comprising standards, ledgers and     floor parts; -   providing the assembly according to claim 19; -   building up a first scaffold bay which comprises four standards, at     least two transverse ledgers and a floor on a first floor level; -   coupling the first preceding-guardrail post to the scaffold bay; -   hooking the guardrail by the first fastening hook thereof into the     first preceding-guardrail holder; -   hooking the second fastening hook of the guardrail into the second     preceding-guardrail holder; and -   coupling the second preceding-guardrail post to the scaffold bay for     placement of a preceding guardrail for the purpose of the protection     of a second scaffold bay which is above the first scaffold bay.

The effects and advantages of the method for arranging a temporary preceding guardrail are the same as the effects and advantages of the preceding-guardrail holder, the assembly, and the scaffolding system according to the invention, in particular those effects and advantages as described in relation to the embodiment described in claim 19.

Further elaborations of the invention are described in the dependent claims and will hereinafter be clarified in more detail on the basis of an example, with reference to the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an example of already known guardrail from the prior art;

FIG. 2 shows an example of an assembly of the already known guardrail from the prior art and a preceding-guardrail holder according to the invention;

FIG. 3 shows the example of FIG. 2 , with a fastening hook of the guardrail received in the fastening hook receiving space, and the guardrail being supported by the preceding-guardrail holder alone;

FIG. 4 shows the example of the preceding-guardrail holder of FIGS. 2 and 3 provided with a first safety element in a first position in which the first safety element hinders a taking-out of the fastening hook out of the fastening hook receiving space other than partly by a turning of the guardrail around a curvature axis;

FIG. 5 shows the example of the preceding-guardrail holder of FIG. 4 with the first safety element in a second position in which the first fastening protection allows taking-out of the fastening hook partly by a translation of the guardrail;

FIG. 6 shows an example of an assembly of a first and a second already known guardrail from the prior art and the preceding-guardrail holder according to the invention;

FIG. 7 shows an example of an assembly of the already known guardrail and two posts each provided with the preceding-guardrail holder according to the invention.

DETAILED DESCRIPTION OF THE FIGURES

In the following detailed description of the figures, with the help of reference numerals reference is made to the example that is represented in the figures. The embodiments that are described in the detailed description, however, are not limited to the example that is shown in the figures but may also be implemented in a different manner than is shown in the example. The embodiments described in the detailed description should therefore be read and understood also without the reference numerals. The various embodiments to be described hereinafter can also be used in combination with each other or independently of each other.

Most generally, the invention provides a preceding-guardrail holder 10 for a scaffolding system comprising standards, ledgers and substantially tube-shaped guardrails 12, 14. The preceding-guardrail holder 10 is configured for cooperation with the guardrails 12, 14 of the scaffolding system.

Each guardrail 12, 14 is provided at a longitudinal end with a fastening hook 16 which has a curvature around a curvature axis 20 which is perpendicular to a longitudinal axis 22 of the guardrail 12, 14. The fastening hook 16 is provided on a radial inner side 24 thereof with a recess 28, while the distance of the recess 28 to a point on a radial outer side 26 of the fastening hook 16 gradually increases from a first point 30 on the radial outer side 26 to a second point 32 on the radial outer side 26 of the fastening hook 16, with the second point 32 being more remote from a center of the guardrail 12, 14 than the first point 30.

The preceding-guardrail holder 10, as is clearly visible in the example of FIG. 4 , is provided with a mounting plate 34 and a retaining plate 36 which extends substantially parallel to the mounting plate 34. The mounting plate 34 and the retaining plate 36 are mutually connected by a first and a second cross connection element 38, 40, both extending perpendicular to the mounting plate 34 and retaining plate 36. The two cross connection elements 38, 40 are mutually spaced apart, and together bound a fastening hook receiving space 42 for receiving the fastening hook 16 of a first guardrail 12 of the above-mentioned guardrails 12, 14 in the fastening hook receiving space 42. The distance between the first and the second cross connection element 38, 40 is such that if the fastening hook 16 is received in the fastening hook receiving space 42, and the first guardrail 12 is not supported otherwise, the recess 28 on the radial inner side 24 of the fastening hook 16 rests on the first cross connection element 38 and the radial outer side 26 of the fastening hook 16 abuts against the second cross connection element 40, as a result of which the first guardrail 12 is supported wholly by the single preceding-guardrail holder 10.

The guardrail 12, 14 with fastening hook 16 is already known. An example is the already mentioned guardrail 14 of DE 101 12 369 A1. The invention merely concerns the preceding-guardrail holder 10 which is configured for cooperation with this, known, guardrail 12, 14. The other effects and advantages of the preceding-guardrail holder 10 have already been described in the summary and these effects and advantages are understood to be inserted here by citation.

In an embodiment, the distance between the first and the second cross connection element 38, 40 is such that if the first guardrail 12 is merely supported by the preceding-guardrail holder 10, the first guardrail 12 makes an angle of 20° to 70° with the horizontal, preferably between 40° and 50°, more preferably about 45°.

The first guardrail 12, as a result, will tend to hang down obliquely. The guardrail 12 can be simply attached at a higher level and be engaged from a lower level.

In an embodiment, of which an example is shown in FIG. 6 , the preceding-guardrail holder 10 is configured for cooperation with a second guardrail 14 of the above-mentioned guardrails 12, 14. If the first guardrail 12 extends on a first side of the preceding-guardrail holder 10 and the recess 28 of the first guardrail 12 engages the first cross connection element 38, the second guardrail 14 extends on a second side of the preceding-guardrail holder 10 and the recess 28 of the second guardrail 14 engages the second cross connection element 40. The second side of the preceding-guardrail holder 10 is located opposite the first side of the preceding-guardrail holder 10. The first cross connection element 38 and the second cross connection element 40 may be placed at a same height.

By placing the cross connection elements 38, 40 at a same height, the fastening hook receiving space 42 becomes symmetrical, as it were. In that case, it makes no difference for the guardrails 12, 14 anymore from which side they are attached to the preceding-guardrail holder 10. In this way, the preceding-guardrail holder 10 can be used to attach a guardrail 12, 14 on both sides. Such a preceding-guardrail holder 10 may for instance be used in a continuous guardrail along a scaffold frame.

In an embodiment, if the fastening hook 16 is received in the fastening hook receiving space 42, the first and the second cross connection element 38, 40 are perpendicular to the longitudinal direction of the first guardrail 12, parallel to the curvature axis 20. Such an orientation provides for a stable, reliable attachment of the first guardrail 12 to the preceding-guardrail holder 10.

This may be realized, for instance, if the fastening hook 16 is a plate-shaped hook and the distance between the mounting plate 34 and the retaining plate 36 is such that the plate-shaped hook is fittingly received in the fastening hook receiving space 42. A plate-shaped hook has for instance a minor cross section in the direction of its curvature axis, whereas a cross section radial to the curvature axis is many times greater. A fastening hook receiving space 42 tailored to this shape has as an effect that the first guardrail 12 cannot turn around a tangent of the fastening hook 16. Accordingly, therefore, the guardrail 12 will not move out of a vertical plane that extends parallel to the longitudinal ledgers of the scaffolding system and will be pivotable in that vertical plane only from the initial oblique position to the eventual horizontal position.

In an embodiment, the preceding-guardrail holder 10 is further provided with a first fastening protection 44 above the fastening hook receiving space 42. The fastening protection 44 is configured for hindering a taking-out of the fastening hook 16 of the first guardrail 12 out of the fastening hook receiving space 42 other than partly by a turning of the first guardrail 12 around the curvature axis 20. If the preceding-guardrail holder 10 in this embodiment is further configured for cooperation with a second guardrail 14 of the above-mentioned guardrails 12, 14, as described above, then the first fastening protection 46 may also be configured for hindering a taking-out of the fastening hook 16 of the second guardrail 14 out of the fastening hook receiving space 42 other than partly by a turning of the second guardrail 14 around the curvature axis 20.

Without further support, the first guardrail 12 continues to hang obliquely in the preceding-guardrail holder 10. By lifting it a little bit, the fastening hook 16, by turning around the curvature axis 20 or an axis parallel thereto, can be taken out of the fastening hook receiving space 42. The fastening protection 44 is so positioned that this movement is not hindered. A translation of the first guardrail 12, for example upwards, still is hindered by the fastening protection. An example of this is shown in FIG. 4 . The blocking of this movement is of importance if the first guardrail 12 is for instance hanging horizontally, for instance because it is supported at a longitudinal end opposite the longitudinal end that is provided with the fastening hook 16. This is for instance the case if the first guardrail is in use and hence extends horizontally. The fastening protection then ensures that the first guardrail 12 cannot be taken or knocked out of the preceding-guardrail holder 10.

The first fastening protection 44 can have a first position in which the first fastening protection 44 hinders a taking-out of the fastening hook 16 out of the fastening hook receiving space 42 other than partly by a turning of the first guardrail 12 around the curvature axis 20. The first fastening protection 44 can additionally have a second position in which the first fastening protection 44 allows taking-out of the fastening hook 16 partly by a translation of the first guardrail 12. An example of such a first fastening protection 44 is the tipping closure shown in the figures. In the example of FIGS. 2, 3, and 4 , the first fastening protection 44 is in the first position. Especially in FIG. 4 it can be properly seen how the first fastening protection 44 hinders a taking-out of the first guardrail 12 by translation. In the example of FIG. 5 , the first fastening protection 44 is in the second position. In this second position it is possible to have the first guardrail 12 make a small turning around the longitudinal axis 22 and then by a translation move it substantially upwards, as a result of which the fastening hook 16 is taken out of the fastening hook receiving space 42 of the preceding-guardrail holder 10. A turning of a few degrees is sufficient then. A turning of for example 5° is sufficient in the example shown to be able to take the first guardrail 10 out of the preceding-guardrail holder 10. The translation may be oriented a little obliquely upward to prevent a collision with the first fastening protection 44. If the first fastening protection 44 is also configured for hindering a taking-out of the fastening hook 16 of the second guardrail 14 out of the fastening hook receiving space 42 other than partly by a turning of the second guardrail 14 around the curvature axis 20, then all that has been described above for the first fastening protection 44 in relation to the first guardrail 12 also holds for the first fastening protection 44 in relation to the second guardrail 14.

Alternatively or additionally to configuring the first fastening protection 44 for hindering a taking-out of the fastening hook 16 of the second guardrail 14 out of the fastening hook receiving space 42 other than partly by a turning of the second guardrail 14 around the curvature axis 20, it is also possible to provide the preceding-guardrail holder 10 with a second fastening protection 46. This second fastening protection 46 is provided above the fastening hook receiving space 42 and is configured for hindering a taking-out of the fastening hook 16 of the second guardrail 14 out of the fastening hook receiving space 42 other than partly by a turning of the second guardrail 14 around the curvature axis 20.

Also this second fastening protection 46 may, analogously to the first fastening protection 44, have a first position in which the second fastening protection 46 hinders a taking-out of the fastening hook 16 of the second guardrail 14 out of the fastening hook receiving space 42 other than partly by a turning of the second guardrail 14 around the curvature axis 20. Also, the second fastening protection 46 may further have a second position in which the second fastening protection 46 allows taking-out of the fastening hook 16 partly by a translation of the second guardrail 14. The operation of the second fastening protection 46 is analogous to that of the above-described first fastening protection 44. Also the second fastening protection 46 may be, for example, the tipping closure shown in the figures.

Both the first fastening protection 44 and the second fastening protection 46, if any, may be provided on the mounting plate 34.

In an embodiment, the mounting plate 34 is provided with screw holes for the purpose of attaching the preceding-guardrail holder 10 to a standard.

In this way, the preceding-guardrail holder 10 can be simply fixed to the scaffold frame. Alternatively, the mounting plate 34 may also be welded or soldered to a component, for example a standard, of the scaffold frame.

The invention provides in addition an assembly for arranging a temporary preceding guardrail on a scaffolding system comprising standards and ledgers. The assembly comprises a substantially tube-shaped guardrail 12 and a first preceding-guardrail holder 10 according to the invention. The guardrail 12 is provided, at a first longitudinal end, with a fastening hook 16 which has a curvature around a first curvature axis 20 which is perpendicular to a longitudinal axis 22 of the guardrail 12. The first fastening hook 16 is provided, on a radial inner side 24 thereof, with a recess 28, while the distance of the recess 28 to a point on a radial outer side 26 of the first fastening hook 16 gradually increases from a first point 30 on the radial outer side 26 to a second point 32 on the radial outer side 26 of the first fastening hook 16, and with the second point 32 being more remote from a center of the guardrail 12 than the first point 30.

The effects and advantages of the assembly have already been described in the summary and these effects and advantages are understood to be inserted here by citation.

In an embodiment, of which an example is shown in FIG. 1 , the guardrail 12 is provided at a second longitudinal end thereof with a second fastening hook 18 which has a curvature around a second curvature axis 20 which is parallel to the first curvature axis 20. The second longitudinal end is located opposite the first longitudinal end of the guardrail 12 and the curvature of the second fastening hook 18 is opposite to the curvature of the first fastening hook 16. The second fastening hook 18, on a radial inner side 24 thereof, is provided with a recess 28, while the distance of the recess 28 to a point on a radial outer side 26 of the second fastening hook 18 gradually increases from a first point 30 on the radial outer side 26 to a second point 32 on the radial outer side 26 of the second fastening hook 18, with the second point 32 being more remote from a center of the guardrail 12 than the first point 30. This assembly may further comprise a second preceding-guardrail holder 48 according to the invention.

The guardrail 12 in this embodiment has a fastening hook 16, 18 at both longitudinal ends. With these, the guardrail 12 can be fastened to both the first and to the second preceding-guardrail holder 10, 48. If the first and the second preceding-guardrail holder 10, 48 are at an equal height, the guardrail 12 is suspended horizontally between them.

In an embodiment, the first fastening hook 16 is implemented as a plate-shaped hook. If the guardrail 12 of the assembly is provided with the second fastening hook 18, the latter too may be implemented as a plate-shaped hook.

The distance between the mounting plate 34 and the retaining plate 36 of the first preceding-guardrail holder 10 and possibly the second preceding-guardrail holder 48 may be such that in the fastening hook receiving space 42 two plate-shaped hooks are receivable.

Plate-shaped hooks have a minor cross section in the direction of their curvature axis 20, whereas a cross section radial to the curvature axis 20 is many time greater. A fastening hook receiving space 42 tailored to this shape has as an advantage that the guardrail 12 cannot turn around a tangent of the first or second fastening hook 16, 18 and, as a consequence, can move substantially exclusively in a vertical plane that extends parallel to the longitudinal ledgers of the scaffolding system.

In an embodiment, of which an example is shown in FIG. 7 , the assembly further comprises a first preceding-guardrail post 50 which at or near an upper side thereof is provided with the first preceding-guardrail holder 10 and at a lower side is configured to be supported by a bracket of the scaffolding system, or a temporary bracket fitted to the scaffolding system. The assembly further comprises a second preceding-guardrail post 52 which, at or near an upper side thereof, is provided with the second preceding-guardrail holder 48 and at a lower side thereof is configured to be supported by a bracket of the scaffolding system or a temporary bracket fitted to the scaffolding system.

With this assembly, the first preceding-guardrail post 50 can be mounted to the scaffold frame, so that the upper side of the first preceding-guardrail post 50 is located above an upper, unprotected floor level. Thereupon the first fastening hook 16 of the guardrail 12 can be received in the fastening hook receiving space 42 of the first preceding-guardrail holder 10. The second preceding-guardrail holder 48 can thereupon be attached to the second fastening hook 18, by inserting the second fastening hook 18 in the fastening hook receiving space 42 of the second preceding-guardrail holder 48. By finally mounting the second preceding-guardrail post 50 to the scaffold frame in such a manner that the upper side of post 50 is located above the upper floor level, the guardrail 12 provides a protection for the respective floor level. The assembly therefore provides a solution for the arranging of a temporary preceding guardrail on an upper floor level, making use of known guardrails 12, 14. The assembly provides a fast solution which can be executed by a single person. After arranging the temporary preceding guardrail 12, the upper floor level can be entered safely. Thereupon a permanent guardrail can be mounted on the scaffold frame, for which the same guardrail 12 can be used.

The invention further provides a scaffolding system comprising standards, ledgers, and the assembly according to the invention.

The effects and advantages of the scaffolding system have already been described in the summary and these effects and advantages are understood to be inserted here by citation.

The invention further provides a method for arranging a temporary preceding guardrail on a scaffolding system comprising standards and ledgers. The method comprises:

-   providing scaffolding components comprising standards, ledgers and     floor parts; -   providing the assembly according to claim 19; -   building up a first scaffold bay which comprises four standards, at     least two transverse ledgers and a floor on a first floor level; -   coupling the first preceding-guardrail post 50 to the scaffold bay; -   hooking the guardrail 12 by the first fastening hook 16 thereof into     the first preceding-guardrail holder 10; -   hooking the second fastening hook 16 of the guardrail 12 into the     second preceding-guardrail holder 48; and -   coupling the second preceding-guardrail post 52 to the scaffold bay     for placement of a preceding guardrail for the purpose of the     protection of a second scaffold bay which is above the first     scaffold bay.

The effects and advantages of the method for arranging a temporary preceding guardrail on a scaffolding system have already been described in the summary and these effects and advantages are understood to be inserted here by citation.

The invention is not limited to the example shown in the figures. The above described embodiments, as already indicated, may also be implemented differently than shown in the example of the figures. The scope of protection is defined by the following claims, in which the reference numerals have no limiting effect.

KEY TO SYMBOLS

-   10 — preceding-guardrail holder -   12 — (first) guardrail -   14 — second guardrail -   16 — (first) fastening hook -   18 — second fastening hook -   20 — curvature axis -   22 — longitudinal axis -   24 — radial inner side -   26 — radial outer side -   28 — recess (in the radial inner side) -   30 — first point (on the radial outer side) -   32 — second point (on the radial outer side) -   34 — mounting plate -   36 — retaining plate -   38 — first cross connection element -   40 — second cross connection element -   42 — fastening hook receiving space -   44 — first fastening protection -   46 — second fastening protection -   48 — second preceding-guardrail holder -   50 — first preceding-guardrail post -   52 — second preceding-guardrail post 

1. A preceding-guardrail holder for a scaffolding system comprising standards, ledgers and substantially tube-shaped guardrails, wherein the preceding-guardrail holder is configured for cooperation with the guardrails of the scaffolding system, wherein each guardrail at a longitudinal end thereof is provided with a fastening hook which has a curvature around a curvature axis which is perpendicular to a longitudinal axis of the guardrail, wherein the fastening hook on a radial inner side is provided with a recess, wherein the distance of the recess to a point on a radial outer side of the fastening hook gradually increases from a first point on the radial outer side to a second point on the radial outer side of the fastening hook, wherein the second point is more remote from a center of the guardrail than the first point, wherein the preceding-guardrail holder is provided with a mounting plate and a retaining plate which extends substantially parallel to the mounting plate, wherein the mounting plate and the retaining plate are mutually connected by a first and a second cross connection element extending perpendicular to the mounting plate and retaining plate, wherein the two cross connection elements are mutually spaced apart and together bound a fastening hook receiving space for receiving in the fastening hook receiving space the fastening hook of a first of said guardrails, wherein the distance between the first and the second cross connection element is such that, if the fastening hook is received in the fastening hook receiving space and the first guardrail is not supported otherwise, the recess on the radial inner side of the fastening hook rests on the first cross connection element and the radial outer side of the fastening hook abuts against the second cross connection element, the first guardrail thereby being wholly supported by the single preceding-guardrail holder.
 2. The preceding-guardrail holder according to claim 1, wherein the distance between the first and the second cross connection element is such that, if the first guardrail is supported merely by the preceding-guardrail holder, the first guardrail makes an angle of 20° to 70° with the horizontal.
 3. The preceding-guardrail holder according to claim 1, configured for cooperation with a second guardrail of said guardrails, wherein, if the first guardrail extends on a first side of the preceding-guardrail holder and the recess of the first guardrail engages the first cross connection element, the second guardrail extends on a second side of the preceding-guardrail holder and the recess of the second guardrail engages the second cross connection element, wherein the second side of the preceding-guardrail holder is located opposite the first side of the preceding-guardrail holder.
 4. The preceding-guardrail holder according to claim 3, wherein the first cross connection element and the second cross connection element are placed at a same height.
 5. The preceding-guardrail holder according to claim 1, wherein, if the fastening hook is received in the fastening hook receiving space, the first and the second cross connection element are perpendicular to the longitudinal direction of the first guardrail, parallel to the curvature axis.
 6. The preceding-guardrail holder according to claim 1, further provided with a first fastening protection above the fastening hook receiving space, configured for hindering a taking-out of the fastening hook of the first guardrail out of the fastening hook receiving space other than partly by a turning of the first guardrail around the curvature axis.
 7. The preceding-guardrail holder according to claim 3, further provided with a first fastening protection above the fastening hook receiving space, configured for hindering a taking-out of the fastening hook of the first guardrail out of the fastening hook receiving space other than partly by a turning of the first guardrail around the curvature axis, wherein the first fastening protection is also configured for hindering a taking-out of the fastening hook of the second guardrail out of the fastening hook receiving space other than partly by a turning of the second guardrail around the curvature axis.
 8. The preceding-guardrail holder according to claim 6, wherein the first fastening protection has a first position in which the first fastening protection hinders a taking-out of the fastening hook out of the fastening hook receiving space other than partly by a turning of the first and possibly second guardrail around the curvature axis, and wherein the first fastening protection has a second position in which the first fastening protection allows taking-out of the fastening hook partly by a translation of the first and possibly second guardrail.
 9. The preceding-guardrail holder according to claim 3, further provided with a first fastening protection above the fastening hook receiving space, configured for hindering a taking-out of the fastening hook of the first guardrail out of the fastening hook receiving space other than partly by a turning of the first guardrail around the curvature axis, and further provided with a second fastening protection above the fastening hook receiving space, configured for hindering a taking-out of the fastening hook of the second guardrail out of the fastening hook receiving space other than partly by a turning of the second guardrail around the curvature axis.
 10. The preceding-guardrail holder according to claim 9, wherein the second fastening protection has a first position in which the second fastening protection hinders a taking-out of the fastening hook out of the fastening hook receiving space other than partly by a turning of the second guardrail around the curvature axis, and wherein the second fastening protection has a second position in which the second fastening protection allows taking-out of the fastening hook partly by a translation of the second guardrail.
 11. The preceding-guardrail holder according to claim 6, wherein the first fastening protection and/or possibly the second fastening protection is a tipping closure.
 12. The preceding-guardrail holder according to claim 6, wherein the first fastening protection and possibly the second fastening protection is provided on the mounting plate.
 13. The preceding-guardrail holder according to claim 1, wherein the mounting plate is provided with screw holes for the purpose of mounting the preceding-guardrail holder to a standard.
 14. An Asssembly for arranging a temporary preceding guardrail on a scaffolding system comprising standards and ledgers, the assembly comprising a substantially tube-shaped guardrail and a first preceding-guardrail holder according to claim 1, wherein the guardrail at a first longitudinal end is provided with a first fastening hook which has a curvature around a first curvature axis which is perpendicular to a longitudinal axis of the guardrail, wherein the first fastening hook on a radial inner side thereof is provided with a recess, wherein the distance of the recess to a point on a radial outer side of the first fastening hook gradually increases from a first point on the radial outer side to a second point on the radial outer side of the first fastening hook, and wherein the second point is more remote from a center of the guardrail than the first point.
 15. The assembly according to claim 14, wherein the guardrail at a second longitudinal end thereof is provided with a second fastening hook which has a curvature around a second curvature axis which is parallel to the first curvature axis, wherein the second longitudinal end is located opposite the first longitudinal end of the guardrail and wherein the curvature of the second fastening hook is opposite to the curvature of the first fastening hook, wherein the second fastening hook on a radial inner side thereof is provided with a recess, wherein the distance of the recess to a point on a radial outer side of the second fastening hook gradually increases from a first point on the radial outer side to a second point on the radial outer side of the second fastening hook, and wherein the second point is more remote from a center of the guardrail than the first point.
 16. The assembly according to claim 14, further comprising a second preceding-guardrail holder.
 17. The assembly according to claim 14, wherein the first fastening hook and possibly the second fastening hook is implemented as a plate-shaped hook.
 18. The assembly according to claim 17, wherein the distance between the mounting plate and the retaining plate of the first preceding-guardrail holder and possibly the second preceding-guardrail holder is such that in the fastening hook receiving space two plate-shaped hooks are receivable.
 19. The assembly according to claim 15, further comprising a first preceding-guardrail post which on or near an upper side thereof is provided with the first preceding-guardrail holder and at a lower side thereof is configured to be supported by a bracket of the scaffolding system, or a temporary bracket on the scaffolding system, and a second preceding-guardrail post which on or near an upper side thereof is provided with a second preceding-guardrail holder and at a lower side thereof is configured to be supported by a bracket of the scaffolding system, or a temporary bracket on the scaffolding system.
 20. A scaffolding system comprising standards, ledgers and the assembly according to claim
 14. 21. A method for arranging a temporary preceding guardrail on a scaffold, the method comprising: providing scaffolding parts comprising standards, ledgers and floor parts; providing the assembly according to claim 19; building up a first scaffold bay which comprises four standards, at least two transverse ledgers and a floor on a first floor level; coupling the first preceding-guardrail post to the scaffold bay; hooking the guardrail by the first fastening hook thereof into the first preceding-guardrail holder; hooking the second fastening hook of the guardrail into the second preceding-guardrail holder; and coupling the second preceding-guardrail post to the scaffold bay for placement of a preceding guardrail for the purpose of protection of a second scaffold bay which is above the first scaffold bay. 